When first diagnosed with Huntington’s disease (HD), you might be overwhelmed with all of the information out there. Here are some basic facts:

  • HD is passed down through generations
  • It worsens over time as it breaks down nerve cells in the brain
  • It affects a person’s behavior, movement, and ability to think and reason
  • Symptoms vary from person to person

Types of Huntington’s disease symptoms

Keep in mind that everyone experiences symptoms differently. Some may show emotions, behavior, and thinking symptoms first, while others may notice movement issues. HD symptoms fall into 3 major categories and can include:

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Thinking and Processing

  • Forgetfulness
  • Difficulty processing information
  • Trouble making decisions
  • Difficulty completing tasks
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Emotions and Behavior

  • Mood swings
  • Irritability
  • Depression
  • Impulse control issues
  • Apathy
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Movement and Balance

  • Uncontrolled movements (chorea)
  • Issues with walking
  • Clumsiness
  • Abnormal eye movements

To learn more about possible HD symptoms and how they may progress, speak to your doctor.

What causes Huntington’s disease?

DNA is like a unique recipe that determines the building blocks for every individual. mRNA follows the DNA’s recipe to make a protein. If there is a mistake in the recipe, there can be a problem with what gets made.

Huntington's disease gene

Genetic testing for Huntington’s disease

There are a few types of genetic tests that a person at risk for HD can take, including:

  • a predictive test—which tests for the gene mutation in someone who isn't showing signs and symptoms
  • a confirmatory test—which confirms an HD diagnosis in someone who is showing clinical symptoms

Your doctor will be able to recommend when to get a confirmatory test. However, the decision of whether or not to get a predictive test is a personal one and there is no “right” decision. Some people opt not to get tested because currently there is no disease-modifying treatment that stops or slows the progression of HD. Others decide to get tested so they can plan ahead before they develop symptoms. Each person must make the decision that is best for him or her. You may want to talk to your general physician, neurologist, or genetic counselor to discuss your options.

If you want to learn more about genetic testing so that you can make an informed decision, it may be a good idea to get it done at a place that is knowledgeable about HD. For example, some centers use the HDSA guidelines.

In addition to a genetic counselor, you may also want to talk with a social worker or psychologist to help process your thoughts about the test and results. If you get tested at a facility that uses the recommended HDSA guidelines, a mental health assessment is required before getting the genetic test.

With so many aspects of genetic testing to consider, it can be both overwhelming and confusing. However, there is a comprehensive checklist to help ensure that you are thinking about all of the pros and cons. This resource also includes topics like timing, impact, the testing process, and anonymous testing.


What do the genes mean?

Everyone has the huntingtin gene. HD is determined by the number of CAG repeats in the huntingtin gene. What really matters is how many CAG repeats someone has within that gene. A higher number of repeats can cause problems for you and your children, as shown in the table below. If you’re at risk for HD, speak to your neurologist if you are considering a genetic test.

Expanded CAG repeats
What it means
26 times or less Considered normal; the person will not develop HD
27-35 The person will not develop HD themselves, but there is a risk of HD in later generations
36-39 Considered abnormal and may or may not result in HD
40 or more Will result in HD
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